The present invention relates generally to the field of manufacture and preparation of roofing sheet material, generally of the asphalt type, and more specifically to a method and apparatus for forming a plurality of holes in the roofing material.
Sheet roofing material is usually prepared by treating a web of roofing felt with asphalt so as to saturate the felt. It is presently desirable to provide the treated web of sheet roofing material with a number of holes or apertures to provide means of escape for air or vapor so that such air or vapor will not be trapped under the roofing material during installation on a roof. A variety of prior art devices and techniques have been employed for the purpose of providing the desired holes or apertures.
One such prior art technique for perforating the web of sheet roofing material involves the use of a needle roll or cylinder and an opposed grooved-in wire brush roll so that the web of sheet material may be passed therebetween and needles carried on the needle roll will penetrate the roofing material so as to form the perforations. The insertion of the needles into the sheet material, however, only causes a separation of the roofing material with little or no removal of the material by the needles. Consequently, the holes formed by the insertion of the needles will have a tendency to close up as a result of forces applied to the sheet material during further treating or manufacturing processes, to be performed on the web, such as further rolling or winding the web into rolls. As a result, this method has been found to be unsatisfactory since air or vapor may yet be trapped under the roofing material during installation on a roof.
A further prior art technique is to utilize a cutting knife mounted on a cutting roll including a surface with a leading end cutting edge and a trailing end cutting edge so that sections of the web of sheet material will be cut-out by the knife element thus removing a certain amount of sheet material from the web. This technique is an improvement over the needle roll technique since the cut-out areas will not completely close up during the winding of the material into rolls because of compressive forces applied thereto. This technique, however, has the further disadvantages of producing waste and requiring complicated and expensive cutting machinery to be employed in the treating or manufacturing process.
The prior art techniques have the further disadvantage of being used during the in-line treating or manufacturing of the sheet material, prior to winding or rolling so that the speed of the manufacturing operation may be hindered or affected by the cutting or needle insertion operation. Further, the prior art techniques require that the devices used to perforate the sheet material be an integral part of the manufacturing process and be performed while the roofing material is in web form so that it can only be done at a particular stage in the treating or manufacturing operation.
It is accordingly one object of the present invention to provide a technique of perforating sheet roofing material which overcomes the disadvantages of the prior art.
It is a further object of the present invention to provide an apparatus and method for forming a plurality of permanent and distinct perforation holes in roofing or other sheet material by punching said holes into the sheet material after the completion of the normal manufacturing process and after the sheet material has been formed into wound rolls for storage or shipment to the place of ultimate use.
Another object of the present invention is to provide an apparatus that is durable, easy-to-use, easy-to-maintain, relatively inexpensive, portable, and separate and distinct from the equipment or in-line operation used in the treating or manufacturing process.
A further more specific object of the present invention is to provide an apparatus for perforating rolls of roofing sheet material by supporting the roll on a spindle of a turret, and moving that spindle into a perforating station where a plurality of hole-punching devices will be actuated to penetrate the roll from at least two different directions.
A further object of the present invention is to provide a method and means for perforating rolled sheet material at any time and any place rather than being restricted to times and places of manufacturing.
The above objects, features and advantages, along with other objects, features and advantages, of the present invention will become more apparent from the detailed description of the invention in conjunction with the accompanying drawings to be described more fully hereinafter.